Multi-layer golf ball

ABSTRACT

Multi-layer golf balls comprising a single- or dual-layer core, an intermediate layer, and an outer cover layer are disclosed. The intermediate layer is formed from a highly neutralized polymer composition and has a surface hardness which is greater than the center hardness of the core and less than the outer surface hardness of the core. The outer surface hardness of the outer cover layer is greater than the outer surface hardness of the core.

FIELD OF THE INVENTION

The present invention generally relates to golf balls, and moreparticularly to golf balls having an intermediate layer formed from anionomer blend composition. The outer surface hardness of theintermediate layer is greater than the center hardness of the core andless than the outer surface hardness of the core.

BACKGROUND OF THE INVENTION

Numerous golf balls having a multilayer construction wherein the corehardness and cover hardness have been variously improved are disclosedin the prior art. For example, U.S. Pat. No. 6,987,159 to Iwamidiscloses a solid golf ball with a solid core and a polyurethane cover,wherein the difference in Shore D hardness between a center portion anda surface portion of the solid core is at least 15, the polyurethanecover has a thickness (t) of not more than 1.0 mm and is formed from acured urethane composition having a Shore D hardness (D) of from 35 to60, and a product of t and D ranges from 10 to 45.

U.S. Pat. No. 7,175,542 to Watanabe et al. discloses a multi-piece solidgolf ball composed of a multilayer core having at least an inner corelayer and an outer core layer, one or more cover layers which enclosethe core, and numerous dimples formed on a surface of the cover layer.The golf ball is characterized in that the following hardness conditionsare satisfied: (1) (JIS-C hardness of cover)—(JIS-C hardness at centerof core)≧27, (2) 23≦(JIS-C hardness at surface of core)—(JIS-C hardnessat center of core)≦40, and (3) 0.50≦[(deflection amount of entirecore)/(deflection amount of inner core layer)]≦0.75.

U.S. Pat. No. 6,679,791 to Watanabe discloses a multi-piece golf ballwhich includes a rubbery elastic core, a cover having a plurality ofdimples on the surface thereof, and at least one intermediate layerbetween the core and the cover. The intermediate layer is composed of aresin material which is harder than the cover. The elastic core has ahardness which gradually increases radially outward from the center tothe surface thereof. The center and surface of the elastic core have ahardness difference of at least 18 JIS-C hardness units.

U.S. Pat. No. 5,782,707 to Yamagishi et al. discloses a three-piecesolid golf ball consisting of a solid core, an intermediate layer, and acover, wherein the hardness is measured by a JIS-C scale hardness meter,the core center hardness is up to 75 degrees, the core surface hardnessis up to 85 degrees, the core surface hardness is higher than the corecenter hardness by 8 to 20 degrees, the intermediate layer hardness ishigher than the core surface hardness by at least 5 degrees, and thecover hardness is lower than the intermediate layer hardness by at least5 degrees.

U.S. Pat. No. 7,887,437 to Sullivan et al. discloses golf ballsconsisting of a dual core and a dual cover, wherein the dual coreconsists of an inner core layer formed from a rubber composition and anouter core layer formed from a highly neutralized polymer composition.The Shore C hardness of the outer core layer's outer surface is greaterthan the material hardness of the inner cover layer, and is preferably75 Shore C or greater.

Additional examples can be found, for example, in U.S. Pat. No.6,686,436 to Iwami, U.S. Pat. No. 6,786,836 to Higuchi et al., U.S. Pat.No. 7,086,969 to Higuchi et al., U.S. Pat. No. 7,153,224 to Higuchi etal., and U.S. Pat. No. 7,226,367 to Higuchi et al.

The present invention provides a novel multilayer golf ball constructionwhich provides desirable spin and distance properties.

SUMMARY OF THE INVENTION

The present invention is directed to a golf ball having a compression offrom 30 to 90 and consisting essentially of a center or a dual core, anintermediate layer, and an outer cover layer. Three-layer golf balls ofthe present invention include a center having a diameter of from 1.25inches to 1.55 inches, a center Shore C hardness (H_(center)) of from 45to 70, an outer surface Shore C hardness (H_(core surface)) of from 80to 95, and are formed from a rubber composition. Four-layer golf ballsof the present invention include a dual core having an outer diameter offrom 1.25 inches to 1.55 inches, a center Shore C hardness (H_(center))of from 45 to 70, an outer surface Shore C hardness (H_(core surface))of from 80 to 95, and consist of a center formed from a first rubbercomposition and an outer core layer formed from a second rubbercomposition. The intermediate layer has an outer surface Shore Chardness (H_(intermediate surface)) of from 55 to 80, a thickness offrom 0.020 inches to 0.120 inches, and is formed from a highlyneutralized polymer composition having a material hardness of from 50Shore C to 80 Shore C. The highly neutralized polymer composition of theintermediate layer comprises the reaction product of an acid copolymerof ethylene and an α,β-unsaturated carboxylic acid, optionally includinga softening monomer selected from the group consisting of alkylacrylates and methacrylates; a non-acid polymer selected from the groupconsisting of polyolefins, polyamides, polyesters, polyethers,polyurethanes, metallocene-catalyzed polymers, single-site catalystpolymerized polymers, ethylene propylene rubber, ethylene propylenediene rubber, styrenic block copolymer rubbers, alkyl acrylate rubbers,and functionalized derivatives thereof; a cation source; and optionally,an organic acid or salt thereof. The acid copolymer is present in thehighly neutralized polymer composition in an amount of from 20 wt % to90 wt % and the non-acid polymer is present in the highly neutralizedpolymer composition in an amount of from 10 wt % to 80 wt %, based onthe combined weight of the acid copolymer and the non-acid polymer.Greater than 70% of all acid groups present in the highly neutralizedpolymer composition are neutralized. The outer cover layer has an outersurface Shore C hardness (H_(outer cover surface)) of from 82 to 99 anda thickness of from 0.020 inches to 0.080 inches.H_(intermediate surface) is greater than H_(center) and less thanH_(core surface). H_(outer cover surface) is greater thanH_(core surface). The difference between H_(core surface) andH_(intermediate surface) is from 5 to 30.

DETAILED DESCRIPTION

Multi-layer golf balls comprising a single- or dual-layer core, anintermediate layer, and an outer cover layer are disclosed. Theintermediate layer is formed from a highly neutralized polymercomposition and has a surface Shore C hardness(H_(intermediate surface)) which is greater than the center Shore Chardness of the core (H_(center)) and less than the outer surface ShoreC hardness of the core (H_(core surface)). The outer surface Shore Chardness of the outer cover layer (H_(outer cover surface)) is greaterthan the outer surface Shore C hardness of the core.

Single-layer cores of the present invention consist of a center having adiameter of 1.00 or 1.20 or 1.25 or 1.30 or 1.35 or 1.40 or 1.50 or 1.51or 1.52 or 1.53 or 1.54 or 1.55 or 1.57 or 1.59 inches, or a diameterwithin a range having a lower limit and an upper limit selected fromthese values.

Dual-layer cores of the present invention consist of a center and anouter core layer. The center has a diameter of 0.75 or 1.00 or 1.20 or1.25 or 1.30 or 1.35 or 1.40 or 1.50 or 1.51 or 1.52 or 1.53 or 1.54 or1.55 or 1.57 inches, or a diameter within a range having a lower limitand an upper limit selected from these values. The outer core layerencloses the center such that the dual core has an overall diameter of1.00 or 1.20 or 1.25 or 1.30 or 1.35 or 1.40 or 1.50 or 1.51 or 1.52 or1.53 or 1.54 or 1.55 or 1.57 or 1.59 inches, or a diameter within arange having a lower limit and an upper limit selected from thesevalues.

Single- and dual-layer cores of the present invention have a centerShore C hardness (H_(center)) of 40 or greater, or 45 or greater, or 50or greater, or 55 or greater, or 60 or greater, or a center Shore Chardness of 40 or 45 or 50 or 55 or 60 or 65 or 70 or 75, or a centerShore C hardness within a range having a lower limit and an upper limitselected from these values, and an outer surface Shore C hardness(H_(core surface)) of 70 or greater, or 75 or greater, or 80 or greater,or an outer surface Shore C hardness of 70 or 75 or 80 or 85 or 90 or95, or an outer surface Shore C hardness within a range having a lowerlimit and an upper limit selected from these values.

Single- and dual-layer cores of the present invention have an overallpositive hardness gradient wherein the center Shore C hardness is atleast 10 Shore C units less than, or at least 15 Shore C units lessthan, or at least 20 Shore C units less than, or at least 25 Shore Cunits less than, or at least 30 Shore C units less than, or at least 35Shore C units less than the outer surface Shore C hardness of the core,or the core has a positive hardness gradient wherein the differencebetween the center Shore C hardness of the core and the outer surfaceShore C hardness of the core is 5 or 10 or 15 or 20 or 25 or 30 or 35 or40 Shore C units or is within a range having a lower limit and an upperlimit selected from these values. In dual core embodiments, the centermay have a negative hardness gradient wherein the interface hardness ofthe center (H_(center interface)) is less than the center hardness, or azero hardness gradient wherein the interface hardness of the center iswithin 1 hardness unit of the center hardness, or a positive hardnessgradient wherein the interface hardness of the center is greater thanthe center hardness. The interface hardness of the center is definedherein as the hardness at a distance of 1 mm inward from the outersurface of the center. In a particular embodiment, the center has anoverall zero hardness gradient; or a positive hardness gradient wherein

-   -   1<H_(center interface)−H_(center)<45,    -   or 1<H_(center interface)−H_(center)<15,    -   or 1<H_(center interface)−H_(center)<5;        or a negative hardness gradient wherein    -   1<H_(center)−H_(center interface)<45,    -   or 1<H_(center)−H_(center interface)<15,    -   or 1<H_(center)−H_(center interface)<5.

The intermediate layer has an outer surface Shore C hardness(H_(intermediate surface)) which is greater than H_(center) and lessthan H_(core surface). In a particular embodiment, the differencebetween H_(core surface) and H_(intermediate surface) is 5 or 10 or 15or 20 or 25 or 30 or 35, or the difference between H_(core surface) andH_(intermediate surface) is within a range having a lower limit and anupper limit selected from these values.

The outer surface Shore C hardness of the intermediate layer istypically 50 or greater, or 55 or greater, or 60 or greater, or 80 orless, or 75 or less, or 70 or less. In a particular embodiment, theintermediate layer has an outer surface Shore C hardness of 50 or 55 or60 or 65 or 70 or 75 or 80, or an outer surface Shore C hardness withina range having a lower limit and an upper limit selected from thesevalues.

The outer cover layer has an outer surface Shore C hardness(H_(outer cover surface)) which is greater than H_(core surface), and,in a particular embodiment, is the highest outer surface Shore Chardness of any layer of the golf ball. In a particular embodiment, thedifference between H_(outer cover surface) and H_(intermediate surface)is 5 or 10 or 15 or 20 or 25 or 30 or 35 or 40 or 45, or the differencebetween H_(outer cover surface) and H_(intermediate surface) is within arange having a lower limit and an upper limit selected from thesevalues.

The outer surface Shore C hardness of the outer cover layer is typicallygreater than 75, or greater than 80, or 85 or greater, or 90 or greater,or 95 or greater. In a particular embodiment, the outer cover layer hasan outer surface Shore C hardness of 80 or 82 or 85 or 90 or 95 or 99,or an outer surface Shore C hardness within a range having a lower limitand an upper limit selected from these values. In another particularembodiment, the outer cover layer has an outer surface Shore D hardnessof 55 or 60 or 65 or 70 or 75 or 80, or an outer surface Shore Dhardness within a range having a lower limit and an upper limit selectedfrom these values.

The core layer(s) are preferably formed from the same or differentrubber compositions. Suitable rubber compositions include a base rubberselected from natural rubber, polybutadiene, polyisoprene, ethylenepropylene rubber (EPR), ethylene-propylene-diene rubber (EPDM), styrenebutadiene rubber, styrenic block copolymer rubbers, butyl rubber,halobutyl rubber, polystyrene elastomers, polyethylene elastomers,polyurethane elastomers, polyurea elastomers, metallocene-catalyzedelastomers and plastomers, acrylonitrile butadiene rubber, copolymers ofisobutylene and para-alkylstyrene, halogenated copolymers of isobutyleneand para-alkylstyrene, copolymers of butadiene with acrylonitrile,polychloroprene, alkyl acrylate rubber, chlorinated isoprene rubber,acrylonitrile chlorinated isoprene rubber, polyalkenamer, phenolformaldehyde, melamine formaldehyde, polyepoxide, polysiloxane,polyester, alkyd, polyisocyanurate, polycyanurate, polyacrylate, andcombinations of two or more thereof. Diene rubbers are preferred,particularly polybutadiene, styrene butadiene, acrylonitrile butadiene,and mixtures of polybutadiene with other elastomers wherein the amountof polybutadiene present greater than 40 wt % based on the totalpolymeric weight of the mixture.

In a particular embodiment, the core is a solid, single layer formedfrom a polybutadiene blend composition comprising a first polybutadieneand a second polybutadiene. In a particular aspect of this embodiment,the core composition further comprises styrene butadiene rubber. Inanother particular aspect of this embodiment, the first polybutadiene ispresent in the core composition in an amount of 50 phr or greater, or 60phr or greater, or 65 phr or greater, or 70 phr or greater, or 75 phr orgreater, or 80 phr or greater. In another particular aspect of thisembodiment, the second polybutadiene is present in the core compositionin an amount of 10 phr or greater, or 15 phr or greater, or 20 phr orgreater. In another particular aspect of this embodiment, the styrenebutadiene rubber is optionally present in the core composition in anamount of 3 phr or greater, or 5 phr or greater. In dual coreembodiments of the present invention, the center and the outer corelayer may be formed from the same or different rubber compositions.

Non-limiting examples of suitable commercially available rubbers areBuna CB high-cis neodymium-catalyzed polybutadiene rubbers, such as BunaCB 23, Buna CB24, and Buna CB high-cis cobalt-catalyzed polybutadienerubbers, such as Buna CB 1203, 1220 and 1221, commercially availablefrom Lanxess Corporation; SE BR-1220, commercially available from TheDow Chemical Company; Europrene® NEOCIS® BR 40 and BR 60, commerciallyavailable from Polimeri Europa®; UBEPOL-BR® rubbers, commerciallyavailable from UBE Industries, Inc.; BR 01, commercially available fromJapan Synthetic Rubber Co., Ltd.; Neodene high-cis neodymium-catalyzedpolybutadiene rubbers, such as Neodene BR 40, commercially availablefrom Karbochem; TP-301 transpolyisoprene, commercially available fromKuraray Co., Ltd.; Vestenamer® polyoctenamer, commercially availablefrom Evonik Industries; Butyl 065 and Butyl 288 butyl rubbers,commercially available from ExxonMobil Chemical Company; Butyl 301 andButyl 101-3, commercially available from Lanxess Corporation; Bromobutyl2224 and Chlorobutyl 1066 halobutyl rubbers, commercially available fromExxonMobil Chemical Company; Bromobutyl X2 and Chlorobutyl 1240halobutyl rubbers, commercially available from Lanxess Corporation;BromoButyl 2255 butyl rubber, commercially available from JapanSynthetic Rubber Co., Ltd.; Vistalon® 404 and Vistalon® 706 ethylenepropylene rubbers, commercially available from ExxonMobil ChemicalCompany; Dutral CO 058 ethylene propylene rubber, commercially availablefrom Polimeri Europa; Nordel® IP NDR 5565 and Nordel® IP 3670ethylene-propylene-diene rubbers, commercially available from The DowChemical Company; EPT1045 and EPT1045 ethylene-propylene-diene rubbers,commercially available from Mitsui Corporation; Buna SE 1721 TEstyrene-butadiene rubbers, commercially available from LanxessCorporation; Afpol 1500 and Afpol 552 styrene-butadiene rubbers,commercially available from Karbochem; Plioflex PLF 1502, commerciallyavailable from Goodyear Chemical; Nipol® DN407 and Nipol® 1041Lacrylonitrile butadiene rubbers, commercially available from ZeonChemicals, L.P.; Neoprene GRT and Neoprene AD30 polychloroprene rubbers;Vamac® ethylene acrylic elastomers, commercially available from E. I. duPont de Nemours and Company; Hytemp® AR12 and AR214 alkyl acrylaterubbers, commercially available from Zeon Chemicals, L.P.; Hypalon®chlorosulfonated polyethylene rubbers, commercially available from E. I.du Pont de Nemours and Company; and Goodyear Budene® 1207 polybutadiene,commercially available from Goodyear Chemical. In a particularembodiment, the core is formed from a rubber composition comprising asthe base rubber a blend of Neodene BR 40 polybutadiene, Budene® 1207polybutadiene, and Buna SB 1502 styrene butadiene rubber. In anotherparticular embodiment, the core is formed from a rubber compositioncomprising as the base rubber a blend of Neodene BR 40 polybutadiene,Buna CB 1221, and core regrind.

The rubber is crosslinked using, for example, a peroxide or sulfur curesystem, C—C initiators, high energy radiation sources capable ofgenerating free radicals, or a combination thereof.

In a particular embodiment, the rubber is crosslinked using a peroxideinitiator and optionally a coagent. Suitable peroxide initiatorsinclude, but are not limited to, organic peroxides, such as dicumylperoxide; n-butyl-4,4-di(t-butylperoxy) valerate;1,1-di(t-butylperoxy)3,3,5-trimethylcyclohexane;2,5-dimethyl-2,5-di(t-butylperoxy) hexane; di-t-butyl peroxide;di-t-amyl peroxide; t-butyl peroxide; t-butyl cumyl peroxide;2,5-dimethyl-2,5-di(t-butylperoxy)hexyne-3;di(2-t-butyl-peroxyisopropyl)benzene; dilauroyl peroxide; dibenzoylperoxide; t-butyl hydroperoxide; lauryl peroxide; benzoyl peroxide; andcombinations thereof. Examples of suitable commercially availableperoxides include, but are not limited to Perkadox® BC dicumyl peroxide,commercially available from Akzo Nobel, and Varox® peroxides, such asVarox® ANS benzoyl peroxide and Varox® 2311,1-di(t-butylperoxy)3,3,5-trimethylcyclohexane, commercially availablefrom RT Vanderbilt Company, Inc.

The amount of peroxide initiator used to form the rubber composition isgenerally at least 0.05 parts by weight per 100 parts of the baserubber, or is 0.05 parts or 0.1 parts or 0.25 parts or 0.6 parts or 0.8parts or 1 part or 1.25 parts or 1.5 parts or 2.0 parts or 2.5 parts or3 parts or 5 parts or 6 parts or 10 parts or 15 parts by weight per 100parts of the base rubber, or is within a range having a lower limit andan upper limit selected from these values.

Coagents are commonly used with peroxides to increase the state of cure.Suitable coagents include, but are not limited to, metal salts ofunsaturated carboxylic acids; unsaturated vinyl compounds andpolyfunctional monomers (e.g., trimethylolpropane trimethacrylate);maleimides (e.g., phenylene bismaleimide); and combinations thereof.Particular examples of suitable metal salts of unsaturated carboxylicacids include, but are not limited to, one or more metal salts ofacrylates, diacrylates, methacrylates, and dimethacrylates, wherein themetal is selected from magnesium, calcium, zinc, aluminum, lithium,nickel, and sodium. In a particular embodiment, the coagent is selectedfrom zinc salts of acrylates, diacrylates, methacrylates,dimethacrylates, and mixtures thereof. In another particular embodiment,the coagent is zinc diacrylate.

When the coagent is zinc diacrylate and/or zinc dimethacrylate, theamount of coagent used to form the rubber composition is generally 1 or5 or 10 or 15 or 19 or 20 or 24 or 25 or 30 or 35 or 40 or 45 or 50 or60 parts by weight per 100 parts of the base rubber, or is within arange having a lower limit and an upper limit selected from thesevalues. When one or more less active coagents are used, such as zincmonomethacrylate and various liquid acrylates and methacrylates, theamount of less active coagent used may be the same as or higher than forzinc diacrylate and zinc dimethacrylate coagents.

In another particular embodiment, the rubber is crosslinked using sulfurand/or an accelerator. Suitable accelerators include, but are notlimited to, guanidines (e.g., diphenyl guanidine, triphenyl guanidine,and di-ortho-tolyl guanidine); thiazoles (e.g., mercaptobenzothiazole,dibenzothiazyldisulfide, sodium salt of mercaptobenzothiazole, zinc saltof mercaptobenzothiazole, and 2,4-dinitrophenyl mercaptobenzothiazole);sulfenamides (e.g., N-cyclohexylbenzothiazylsulfenamide,N-oxydiethylbenzothiazylsulfenamide, N-t-butylbenzothiazylsulfenamide,and N,N′-dicyclohexylbenzothiazylsulfenamide); thiuram sulfides (e.g.,tetramethyl thiuram disulfide, tetraethyl thiuram disulfide,tetrabutylthiuram disulfide, tetramethyl thiuram monosulfide,dipentamethylene thiuram tetrasulfate, 4-morpholinyl-2-benzothiazoledisulfide, and dipentamethylenethiuram hexasulfide); dithiocarbamates(e.g., piperidine pentamethylene dithiocarbamate, zinc diethyldithiocarbamate, sodium diethyl dithiocarbamate, zinc ethyl phenyldithiocarbamate, and bismuth dimethyldithiocarbamate); thioureas (e.g.,ethylene thiourea, N,N′-diethylthiourea, and N,N′-diphenylthiourea);xanthates (e.g., zinc isopropyl xanthate, sodium isopropyl xanthate, andzinc butyl xanthate); dithiophosphates; and aldehyde amines (e.g.,hexamethylene tetramine and ethylidene aniline).

The crosslinking system optionally includes one or more activatorsselected from metal oxides (e.g., zinc oxide and magnesium oxide), andfatty acids and salts of fatty acids (e.g., stearic acid, zinc stearate,oleic acid, and dibutyl ammonium oleate).

The rubber composition optionally includes a scorch retarder to preventscorching of the rubber during processing before vulcanization. Suitablescorch retarders include, but are not limited to, salicylic acid,benzoic acid, acetylsalicylic acid, phthalic anhydride, sodium acetate,and N-cyclohexylthiophthalimide.

The rubber composition optionally includes one or more antioxidants toinhibit or prevent the oxidative degradation of the base rubber. Someantioxidants also act as free radical scavengers; thus, whenantioxidants are included in the composition, the amount of initiatoragent used may be as high as or higher than the amounts disclosedherein. Suitable antioxidants include, but are not limited to,hydroquinoline antioxidants, phenolic antioxidants, and amineantioxidants.

The rubber composition optionally includes a soft and fast agentselected from organosulfur and metal-containing organosulfur compounds;organic sulfur compounds, including mono, di, and polysulfides, thiol,and mercapto compounds; inorganic sulfide compounds; blends of anorganosulfur compound and an inorganic sulfide compound; Group VIAcompounds; substituted and unsubstituted aromatic organic compounds thatdo not contain sulfur or metal; aromatic organometallic compounds;hydroquinones; benzoquinones; quinhydrones; catechols; resorcinols; andcombinations thereof. In a particular embodiment, the soft and fastagent is selected from zinc pentachlorothiophenol,pentachlorothiophenol, ditolyl disulfide, diphenyl disulfide, dixylyldisulfide, 2-nitroresorcinol, and combinations thereof.

The rubber composition optionally contains one or more fillers.Exemplary fillers include precipitated hydrated silica, clay, talc,asbestos, glass fibers, aramid fibers, mica, calcium metasilicate, zincsulfate, barium sulfate, zinc sulfide, lithopone, silicates, siliconcarbide, diatomaceous earth, carbonates (e.g., calcium carbonate, zinccarbonate, barium carbonate, and magnesium carbonate), metals (e.g.,titanium, tungsten, aluminum, bismuth, nickel, molybdenum, iron, lead,copper, boron, cobalt, beryllium, zinc, and tin), metal alloys (e.g.,steel, brass, bronze, boron carbide whiskers, and tungsten carbidewhiskers), oxides (e.g., zinc oxide, tin oxide, iron oxide, calciumoxide, aluminum oxide, titanium dioxide, magnesium oxide, and zirconiumoxide), particulate carbonaceous materials (e.g., graphite, carbonblack, cotton flock, natural bitumen, cellulose flock, and leatherfiber), microballoons (e.g., glass and ceramic), fly ash, core materialthat is ground and recycled, nanofillers and combinations thereof.

The rubber composition may also contain one or more additives selectedfrom processing aids, such as transpolyisoprene (e.g., TP-301transpolyisoprene, commercially available from Kuraray Co., Ltd.),transbutadiene rubber, and polyalkenamer rubber; processing oils;plasticizers; coloring agents; fluorescent agents; chemical blowing andfoaming agents; defoaming agents; stabilizers; softening agents; impactmodifiers; free radical scavengers; antiozonants (e.g.,p-phenylenediames); and the like.

Suitable types and amounts of rubber, initiator agent, coagent, filler,and additives are more fully described in, for example, U.S. Pat. Nos.6,566,483, 6,695,718, 6,939,907, 7,041,721 and 7,138,460, the entiredisclosures of which are hereby incorporated herein by reference.Particularly suitable diene rubber compositions are further disclosed,for example, in U.S. Patent Application Publication No. 2007/0093318,the entire disclosure of which is hereby incorporated herein byreference.

The intermediate layer has a thickness of 0.020 or 0.030 or 0.060 or0.120 inches, or a thickness within a range having a lower limit and anupper limit selected from these values.

The intermediate layer composition has a solid sphere coefficient ofrestitution (“COR”) of from 0.700 to 0.850. For purposes of the presentdisclosure, the “solid sphere COR” of a composition refers to the COR ofa 1.550 inch solid sphere formed from the composition.

The intermediate layer composition has a solid sphere compression offrom −50 to 50. For purposes of the present disclosure, the “solidsphere compression” of a composition refers to the compression of a1.550 inch solid sphere formed from the composition. In a particularembodiment, the ratio of the compression of the golf ball to the solidsphere compression of the intermediate layer composition is less than1.00.

The intermediate layer is preferably formed from a highly resilientthermoplastic polymer such as a highly neutralized polymer (“HNP”)composition. Particularly suitable HNP compositions for forming theintermediate layer are HNP blend compositions having a material hardnessof from 50 Shore C to 80 Shore C and comprising the reaction product ofan acid copolymer, a non-acid polymer, a cation source, and optionallyan organic acid or salt thereof. For purposes of the present invention,maleic anhydride modified polymers are defined herein as a non-acidpolymer despite having anhydride groups that can ring-open to the acidform during processing of the polymer to form the HNP compositionsherein. The maleic anhydride groups are grafted onto a polymer, arepresent at relatively very low levels, and are not part of the polymerbackbone, as is the case with the acid copolymers.

In a particular embodiment, the acid copolymer is present in an amountof from 20 wt % to 90 wt % and the non-acid polymer is present in anamount of from 10 wt % to 80 wt %, based on the combined weight of theacid copolymer and the non-acid polymer. In another particularembodiment, the acid copolymer is present in an amount of from 20 wt %to 45 wt % and the non-acid polymer is present in an amount of from 55wt % to 80 wt %, based on the combined weight of the acid copolymer andthe non-acid polymer. In another particular embodiment, the acidcopolymer is present in an amount of from 55 wt % to 90 wt % and thenon-acid polymer is present in an amount of from 10 wt % to 45 wt %,based on the combined weight of the acid copolymer and the non-acidpolymer.

Preferred acid copolymers are copolymers of an α-olefin and a C₃-C₈α,β-ethylenically unsaturated carboxylic acid, optionally including asoftening monomer selected from the group consisting of alkyl acrylatesand methacrylates. It is understood that the acid copolymer may be ablend of two or more different acid copolymers. The acid is typicallypresent in the acid copolymer in an amount within a range having a lowerlimit of 1 or 10 or 12 or 15 or 20 wt % and an upper limit of 25 or 30or 35 or 40 wt %, based on the total weight of the acid copolymer. Theα-olefin is preferably selected from ethylene and propylene. The acid ispreferably selected from (meth) acrylic acid, ethacrylic acid, maleicacid, crotonic acid, fumaric acid, and itaconic acid. (Meth) acrylicacid is particularly preferred. Suitable acid copolymers includepartially neutralized acid polymers. Examples of suitable partiallyneutralized acid polymers include, but are not limited to, Surlyn®ionomers, commercially available from E. I. du Pont de Nemours andCompany; AClyn® ionomers, commercially available from HoneywellInternational Inc.; and Iotek® ionomers, commercially available fromExxonMobil Chemical Company. Particularly suitable are DuPont® HPF 1000,HPF 2000, HPF AD1035, and HPF AD1035 Soft, ionomeric materialscommercially available from E. I. du Pont de Nemours and Company.Suitable acid copolymers also include blends of two or more thereof.

Also suitable are the commercially available acid polymers given inTable 1 below.

TABLE 1 Melt Index Softening (2.16 kg, Acid Monomer 190° C., AcidPolymer (wt %) (wt %) g/10 min) Nucrel ® 9-1 methacrylic acid n-butylacrylate 25 (9.0) (23.5) Nucrel ® 599 methacrylic acid none 450 (10.0)Nucrel ® 960 methyacrylic acid none 60 (15.0) Nucrel ® 0407 methacrylicacid none 7.5 (4.0) Nucrel ® 0609 methacrylic acid none 9 (6.0) Nucrel ®1214 methacrylic acid none 13.5 (12.0) Nucrel ® 2906 methacrylic acidnone 60 (19.0) Nucrel ® 2940 methacrylic acid none 395 (19.0) Nucrel ®30707 acrylic acid none 7 (7.0) Nucrel ® 31001 acrylic acid none 1.3(9.5) Nucrel ® AE methacrylic acid isobutyl acrylate 11 (2.0) (6.0)Nucrel ® 2806 acrylic acid none 60 (18.0) Nucrel ® 0403 methacrylic acidnone 3 (4.0) Nucrel ® 925 methacrylic acid none 25 (15.0) Escor ® AT-310acrylic acid methyl acrylate 6 (6.5) (6.5) Escor ® AT-325 acrylic acidmethyl acrylate 20 (6.0) (20.0) Escor ® AT-320 acrylic acid methylacrylate 5 (6.0) (18.0) Escor ® 5070 acrylic acid none 30 (9.0) Escor ®5100 acrylic acid none 8.5 (11.0) Escor ® 5200 acrylic acid none 38(15.0) A-C ® 5120 acrylic acid none not reported (15) A-C ® 540 acrylicacid none not reported (5) A-C ® 580 acrylic acid none not reported (10)Primacor ® 3150 acrylic acid none 5.8 (6.5) Primacor ® 3330 acrylic acidnone 11 (3.0) Primacor ® 5985 acrylic acid none 240 (20.5) Primacor ®5986 acrylic acid none 300 (20.5) Primacor ® 5980I acrylic acid none 300(20.5) Primacor ® 5990I acrylic acid none 1300 (20.0) XUS 60751.17acrylic acid none 600 (19.8) XUS 60753.02L acrylic acid none 60 (17.0)Nucrel ® acid polymers are commercially available from E. I. du Pont deNemours and Company. Escor ® acid polymers are commercially availablefrom ExxonMobil Chemical Company. A-C ® acid polymers are commerciallyavailable from Honeywell International Inc. Primacor ® acid polymers andXUS acid polymers are commercially available from The Dow ChemicalCompany.

Additional suitable acid polymers are more fully described, for example,in U.S. Pat. Nos. 6,562,906, 6,762,246, and 6,953,820 and U.S. PatentApplication Publication Nos. 2005/0049367, 2005/0020741, and2004/0220343, the entire disclosures of which are hereby incorporatedherein by reference.

The non-acid polymer is preferably selected from the group consisting ofpolyolefins, polyamides, polyesters, polyethers, polyurethanes,metallocene-catalyzed polymers, single-site catalyst polymerizedpolymers, ethylene propylene rubber, ethylene propylene diene rubber,styrenic block copolymer rubbers, alkyl acrylate rubbers, chlorinatedpolyethylene, polyvinyl chloride, chlorinated polyvinyl chloride, andfunctionalized derivatives thereof.

In a particular embodiment, the non-acid polymer is an elastomericpolymer selected from the group consisting of:

(a) ethylene-alkyl acrylate polymers, particularly polyethylene-butylacrylate, polyethylene-methyl acrylate, and polyethylene-ethyl acrylate;

(b) metallocene-catalyzed polymers;

(c) ethylene-butyl acrylate-carbon monoxide polymers and ethylene-vinylacetate-carbon monoxide polymers;

(d) polyethylene-vinyl acetates;

(e) ethylene-alkyl acrylate polymers containing a cure site monomer;

(f) ethylene-propylene rubbers and ethylene-propylene-diene monomerrubbers;

(g) olefinic ethylene elastomers, particularly ethylene-octene polymers,ethylene-butene polymers, ethylene-propylene polymers, andethylene-hexene polymers;

(h) styrenic block copolymers;

(i) polyester elastomers;

(j) polyamide elastomers;

(k) polyolefin rubbers, particularly polybutadiene, polyisoprene, andstyrene-butadiene rubber; and

(l) thermoplastic polyurethanes.

Examples of particularly suitable commercially available non-acidpolymers include, but are not limited to, Lotader® ethylene-alkylacrylate polymers and Lotryl® ethylene-alkyl acrylate polymers, andparticularly Lotader® 4210, 4603, 4700, 4720, 6200, 8200, and AX8900commercially available from Arkema Corporation; Elvaloy® ACethylene-alkyl acrylate polymers, and particularly AC 1224, AC 1335, AC2116, AC3117, AC3427, and AC34035, commercially available from E. I. duPont de Nemours and Company; Fusabond® elastomeric polymers, such asethylene vinyl acetates, polyethylenes, metallocene-catalyzedpolyethylenes, ethylene propylene rubbers, and polypropylenes, andparticularly Fusabond® N525, C190, C250, A560, N416, N493, N614, P614,M603, E100, E158, E226, E265, E528, and E589, commercially availablefrom E. I. du Pont de Nemours and Company; Honeywell A-C polyethylenesand ethylene maleic anhydride copolymers, and particularly A-C 5180, A-C575, A-C 573, A-C 655, and A-C 395, commercially available fromHoneywell; Nordel® IP rubber, Elite® polyethylenes, Engage® elastomers,and Amplify® functional polymers, and particularly Amplify® GR 207, GR208, GR 209, GR 213, GR 216, GR 320, GR 380, and EA 100, commerciallyavailable from The Dow Chemical Company; Enable® metallocenepolyethylenes, Exact® plastomers, Vistamaxx® propylene-based elastomers,and Vistalon® EPDM rubber, commercially available from ExxonMobilChemical Company; Starflex® metallocene linear low density polyethylene,commercially available from LyondellBasell; Elvaloy® HP4051, HP441,HP661 and HP662 ethylene-butyl acrylate-carbon monoxide polymers andElvaloy® 741, 742 and 4924 ethylene-vinyl acetate-carbon monoxidepolymers, commercially available from E. I. du Pont de Nemours andCompany; Evatane® ethylene-vinyl acetate polymers having a vinyl acetatecontent of from 18 to 42%, commercially available from ArkemaCorporation; Elvax® ethylene-vinyl acetate polymers having a vinylacetate content of from 7.5 to 40%, commercially available from E. I. duPont de Nemours and Company; Vamac® G terpolymer of ethylene,methylacrylate and a cure site monomer, commercially available from E.I. du Pont de Nemours and Company; Vistalon® EPDM rubbers, commerciallyavailable from ExxonMobil Chemical Company; Kraton® styrenic blockcopolymers, and particularly Kraton® FG1901GT, FG1924GT, and RP6670GT,commercially available from Kraton Performance Polymers Inc.; Septon®styrenic block copolymers, commercially available from Kuraray Co.,Ltd.; Hytrel® polyester elastomers, and particularly Hytrel® 3078, 4069,and 556, commercially available from E. I. du Pont de Nemours andCompany; Riteflex® polyester elastomers, commercially available fromCelanese Corporation; Pebax® thermoplastic polyether block amides, andparticularly Pebax® 2533, 3533, 4033, and 5533, commercially availablefrom Arkema Inc.; Affinity® and Affinity® GA elastomers, Versify®ethylene-propylene copolymer elastomers, and Infuse® olefin blockcopolymers, commercially available from The Dow Chemical Company;Exxelor® polymer resins, and particularly Exxelor® PE 1040, PO 1015, PO1020, VA 1202, VA 1801, VA 1803, and VA 1840, commercially availablefrom ExxonMobil Chemical Company; and Royaltuf® EPDM, and particularlyRoyaltuf® 498 maleic anhydride modified polyolefin based on an amorphousEPDM and Royaltuf®485 maleic anhydride modified polyolefin based on ansemi-crystalline EPDM, commercially available from Chemtura Corporation.

In a particular embodiment, the intermediate layer is formed from ahighly neutralized polymer composition comprising the reaction productof (a) an acid polymer selected from E/X and E/X/Y copolymers ofethylene and an acid, particularly methacrylic acid and acrylic acid,optionally including a softening monomer selected from the groupconsisting of alkyl acrylates and methacrylates; (b) a non-acid polymerselected from maleic anhydride-modified polyolefins; (c) a cationsource; and optionally (d) an organic acid or salt thereof.

Suitable organic acids are aliphatic organic acids, aromatic organicacids, saturated mono-functional organic acids, unsaturatedmonofunctional organic acids, multi-unsaturated mono-functional organicacids, dimerized derivatives thereof, and blends of two or more thereof.Particular examples of suitable organic acids include, but are notlimited to, caproic acid, caprylic acid, capric acid, lauric acid,stearic acid, behenic acid, erucic acid, oleic acid, linoleic acid,myristic acid, benzoic acid, palmitic acid, phenylacetic acid,naphthalenoic acid, dimerized derivatives thereof, and blends of two ormore thereof. Suitable organic acids are more fully described, forexample, in U.S. Pat. No. 6,756,436, the entire disclosure of which ishereby incorporated herein by reference. In a particular embodiment, theorganic acid or salt thereof is used in an amount such that the organicacid or salt thereof is present in the intermediate layer composition inan amount of from 10 wt % to 60 wt %, or within a range having a lowerlimit of 10 or 20 or 30 or 40 wt % and an upper limit of 40 or 50 or 60wt %, based on the total weight of the intermediate layer composition.

The acid copolymer and non-acid polymer are combined and reacted with acation source, such that at least 70%, or at least 80%, or at least 90%,or at least 95%, or 100%, of all acid groups present are neutralized.The present invention is not meant to be limited by a particular orderfor combining and reacting the acid copolymer, non-acid polymer andcation source. When the acid copolymer is partially or highlyneutralized prior to forming the intermediate layer composition, thepartially or highly neutralized acid copolymer may be diluted with asecond acid copolymer to reduce the level of neutralization in the finalcomposition.

Suitable cation sources include, but are not limited to, metal ions andcompounds of alkali metals, alkaline earth metals, and transitionmetals; metal ions and compounds of rare earth elements; ammonium saltsand monoamine salts; and combinations thereof. Preferred cation sourcesare metal ions and compounds of magnesium, sodium, potassium, cesium,calcium, barium, manganese, copper, zinc, tin, lithium, and rare earthmetals.

The HNP composition of the intermediate layer optionally comprisesadditive(s) and/or filler(s). Suitable additives and fillers include,but are not limited to, chemical blowing and foaming agents, opticalbrighteners, coloring agents, fluorescent agents, whitening agents, UVabsorbers, light stabilizers, defoaming agents, processing aids, mica,talc, nano-fillers, antioxidants, stabilizers, softening agents,fragrance components, plasticizers, impact modifiers, TiO₂, acidcopolymer wax, surfactants, and fillers, such as zinc oxide, tin oxide,barium sulfate, zinc sulfate, calcium oxide, calcium carbonate, zinccarbonate, barium carbonate, clay, tungsten, tungsten carbide, silica,lead silicate, regrind (recycled material), and mixtures thereof.

The golf ball subassembly comprising the core and the intermediate layeris enclosed with a relatively hard outer cover layer.

The outer cover layer has a thickness of 0.020 or 0.030 or 0.060 or0.080 or 0.120 inches, or a thickness within a range having a lowerlimit and an upper limit selected from these values.

The outer cover layer composition has a solid sphere COR of from 0.725to 0.820, and a solid sphere compression of from 80 to 180.

The outer cover layer is preferably formed from a composition having amaterial hardness of 80 or 85 or 90 or 95 Shore C, or a materialhardness within a range having a lower limit and an upper limit selectedfrom these values.

Suitable outer cover layer materials include, but are not limited to,ionomer resins and blends thereof (e.g., Surlyn® ionomer resins andDuPont® HPF 1000 and HPF 2000, commercially available from E. I. du Pontde Nemours and Company; Iotek® ionomers, commercially available fromExxonMobil Chemical Company; Amplify® IO ionomers of ethylene acrylicacid copolymers, commercially available from The Dow Chemical Company;and Clarix® ionomer resins, commercially available from A. SchulmanInc.); polyurethanes; polyureas; copolymers and hybrids of polyurethaneand polyurea; polyethylene, including, for example, low densitypolyethylene, linear low density polyethylene, and high densitypolyethylene; polypropylene; rubber-toughened olefin polymers; acidcopolymers, e.g., (meth)acrylic acid, which do not become part of anionomeric copolymer; plastomers; flexomers; styrene/butadiene/styreneblock copolymers; styrene/ethylene/butylene/styrene block copolymers;dynamically vulcanized elastomers; ethylene vinyl acetates; ethylenemethyl acrylates; polyvinyl chloride resins; polyamides, amide-esterelastomers, and graft copolymers of ionomer and polyamide, including,for example, Pebax® thermoplastic polyether block amides, commerciallyavailable from Arkema Inc; crosslinked trans-polyisoprene and blendsthereof; polyester-based thermoplastic elastomers, such as Hytrel®,commercially available from E. I. du Pont de Nemours and Company;polyurethane-based thermoplastic elastomers, such as Elastollan®,commercially available from BASF; synthetic or natural vulcanizedrubber; and combinations thereof. Suitable cover materials andconstructions also include, but are not limited to, those disclosed inU.S. Pat. Nos. 6,117,025, 6,767,940, and 6,960,630, the entiredisclosures of which are hereby incorporated herein by reference.

Polyurethanes, polyureas, and copolymers and blends thereof areparticularly suitable for forming the outer cover layer in dual-layercovers. When used as cover layer materials, polyurethanes and polyureascan be thermoset or thermoplastic. Thermoset materials can be formedinto golf ball layers by conventional casting or reaction injectionmolding techniques. Thermoplastic materials can be formed into golf balllayers by conventional compression or injection molding techniques.

Suitable polyurethane cover materials are further disclosed in U.S. Pat.Nos. 5,334,673, 6,506,851, 6,756,436, and 7,105,623, the entiredisclosures of which are hereby incorporated herein by reference.Suitable polyurea cover materials are further disclosed in U.S. Pat.Nos. 5,484,870, 6,835,794 and 7,378,483, and U.S. Patent ApplicationPublication No. 2008/0064527, the entire disclosures of which are herebyincorporated herein by reference. Suitable polyurethane-urea covermaterials include polyurethane/polyurea blends and copolymers comprisingurethane and urea segments, as disclosed in U.S. Patent ApplicationPublication No. 2007/0117923, the entire disclosure of which is herebyincorporated herein by reference.

Particularly preferred ionomeric outer cover layer compositions include:

-   -   (a) a composition comprising a “high acid ionomer” (i.e., having        an acid content of greater than 16 wt %), such as Surlyn 8150®;    -   (b) a composition comprising a high acid ionomer and a maleic        anhydride-grafted non-ionomeric polymer (e.g., Fusabond®        functionalized polymers). A particularly preferred blend of high        acid ionomer and maleic anhydride-grafted polymer is a 84 wt        %/16 wt % blend of Surlyn 8150® and Fusabond®. Blends of high        acid ionomers with maleic anhydride-grafted polymers are further        disclosed, for example, in U.S. Pat. Nos. 6,992,135 and        6,677,401, the entire disclosures of which are hereby        incorporated herein by reference;    -   (c) a composition comprising a 50/45/5 blend of Surlyn®        8940/Surlyn® 9650/Nucrel® 960, preferably having a material        hardness of from 80 to 85 Shore C;    -   (d) a composition comprising a 50/25/25 blend of Surlyn®        8940/Surlyn® 9650/Surlyn® 9910, preferably having a material        hardness of about 90 Shore C;    -   (e) a composition comprising a 50/50 blend of Surlyn®        8940/Surlyn® 9650, preferably having a material hardness of        about 86 Shore C;    -   (f) a composition comprising a blend of Surlyn® 7940/Surlyn®        8940, optionally including a melt flow modifier;    -   (g) a composition comprising a blend of a first high acid        ionomer and a second high acid ionomer, wherein the first high        acid ionomer is neutralized with a different cation than the        second high acid ionomer (e.g., 50/50 blend of Surlyn® 8150 and        Surlyn® 9150), optionally including one or more melt flow        modifiers such as an ionomer, ethylene-acid copolymer or ester        terpolymer;    -   (h) a composition comprising a blend of a first high acid        ionomer and a second high acid ionomer, wherein the first high        acid ionomer is neutralized with a different cation than the        second high acid ionomer, and from 0 to 10 wt % of an        ethylene/acid/ester ionomer wherein the ethylene/acid/ester        ionomer is neutralized with the same cation as either the first        high acid ionomer or the second high acid ionomer or a different        cation than the first and second high acid ionomers (e.g., a        blend of 40-50 wt % Surlyn® 8140, 40-50 wt % Surlyn® 9120, and        0-10 wt % Surlyn® 6320);    -   (i) a composition comprising a 60/25/15 blend of Surlyn®        9945/Surlyn® 8940/Surlyn® 8320;    -   (j) a composition comprising a 60/40 blend of Surlyn®        9945/Surlyn® 8320;    -   (k) a composition comprising an 80/20 blend of Surlyn®        9945/Surlyn® 8320;    -   (l) a composition comprising a 60/25/15 blend of Surlyn®        9945/Surlyn® 8940/Surlyn® AD1022;

(m) a composition comprising a 60/25/15 blend of Surlyn® 9945/Surlyn®8940/Surlyn® AD1043;

-   -   (n) a composition comprising a 60/40 blend of Surlyn®        9945/Surlyn® AD1022;    -   (o) a composition comprising a 60/40 blend of Surlyn®        9945/Surlyn® AD1043;    -   (p) a composition comprising a single ionomer, wherein the        ionomer is Surlyn® AD1043; and    -   (q) a composition comprising a 57/20/23 blend of Surlyn®        7940/Surlyn® 8945/Fusabond® N525.

Surlyn 8150®, Surlyn® 8940, Surlyn® 8140, and Suryln® 8320 are differentgrades of E/MAA copolymer in which the acid groups have been partiallyneutralized with sodium ions. Surlyn® 9650, Surlyn® 9910, Surlyn® 9150,Surlyn® 9120 and Surlyn® 9945 are different grades of E/MAA copolymer inwhich the acid groups have been partially neutralized with zinc ions.Surlyn® 7940 is an E/MAA copolymer in which the acid groups have beenpartially neutralized with lithium ions. Surlyn® 6320 is a very lowmodulus magnesium ionomer with a medium acid content. Nucrel® 960 is anE/MAA copolymer resin nominally made with 15 wt % methacrylic acid.Fusabond® 525D is a metallocene-catalyzed polyethylene. Surlyn®ionomers, Fusabond® polymers, and Nucrel® copolymers are commerciallyavailable from E. I. du Pont de Nemours and Company.

Suitable ionomers also include polypropylene ionomers, including graftedpolypropylene ionomers. Examples of commercially available polypropyleneionomers include, but are not limited to, Clarix® 130640 and 230620acrylic acid-grafted polypropylene ionomers, commercially available fromA. Schulman Inc., and Priex® 40101, 42101, 45101, and 48101, maleicanhydride-grafted polypropylene ionomers, commercially available fromSolvay Engineered Polymers, Inc.

Suitable ionomers also include polyester ionomers, including, but notlimited to, those disclosed, for example, in U.S. Pat. Nos. 6,476,157and 7,074,465, the entire disclosures of which are hereby incorporatedherein by reference.

Suitable ionomers also include low molecular weight ionomers, such asAClyn® 201, 201A, 295, 295A, 246, 246A, 285, and 285A low molecularweight ionomers, commercially available from Honeywell InternationalInc.

Suitable ionomers also include ionomer compositions comprising anionomer and potassium ions, such as those disclosed, for example, inU.S. Pat. No. 7,825,191, the entire disclosure of which is herebyincorporated herein by reference.

Ionomeric cover compositions can be blended with non-ionic thermoplasticresins, particularly to manipulate product properties. Examples ofsuitable non-ionic thermoplastic resins include, but are not limited to,polyurethane, poly-ether-ester, poly-amide-ether, polyether-urea,thermoplastic polyether block amides (e.g., Pebax® block copolymers,commercially available from Arkema Inc.), styrene-butadiene-styreneblock copolymers, styrene(ethylene-butylene)-styrene block copolymers,polyamides, polyesters, polyolefins (e.g., polyethylene, polypropylene,ethylene-propylene copolymers, polyethylene-(meth)acrylate,polyethylene-(meth)acrylic acid, functionalized polymers with maleicanhydride grafting, Fusabond® functionalized polymers commerciallyavailable from E. I. du Pont de Nemours and Company, functionalizedpolymers with epoxidation, elastomers (e.g., ethylene propylene dienemonomer rubber, metallocene-catalyzed polyolefin) and ground powders ofthermoset elastomers.

Ionomer golf ball cover compositions may include a flow modifier, suchas, but not limited to, acid copolymer resins (e.g., Nucrel® acidcopolymer resins, and particularly Nucrel® 960, commercially availablefrom E. I. du Pont de Nemours and Company), performance additives (e.g.,A-C® performance additives, particularly A-C® low molecular weightionomers and copolymers, A-C® oxidized polyethylenes, and A-C® ethylenevinyl acetate waxes, commercially available from Honeywell InternationalInc.), fatty acid amides (e.g., ethylene bis-stearamide and ethylenebis-oleamide), and fatty acids and salts thereof.

Non-limiting examples of particularly preferred ionomeric cover layerformulations are shown in Table 2 below.

TABLE 2 Cover Layer Surlyn ® 8150, Fusabond ®, Shore C Material wt % wt% Hardness* 1 89 11 91.2 2 84 16 89.8 3 84 16 90.4 4 84 16 89.6 5 81 1988.9 6 80 20 89.1 7 78 22 88.1 8 76 24 87.6 9 76 24 87.2 10 73 27 86.611 71 29 86.7 12 67 33 84.0 *Flex bars of each blend composition wereformed and evaluated for hardness according to ASTM D2240 following 10days of aging at 50% relative humidity and 23° C.

Suitable ionomeric cover materials are further disclosed, for example,in U.S. Patent Application Publication Nos. 2005/0049367, 2005/0148725,2005/0020741, 2004/0220343, and 2003/0130434, and U.S. Pat. Nos.5,587,430, 5,691,418, 5,866,658, 6,100,321, 6,562,906, 6,653,382,6,756,436, 6,777,472, 6,762,246, 6,815,480, 6,894,098, 6,919,393, and6,953,820, the entire disclosures of which are hereby incorporatedherein by reference.

Golf ball cover compositions may include a flow modifier, such as, butnot limited to, Nucrel® acid copolymer resins, and particularly Nucrel®960. Nucrel® acid copolymer resins are commercially available from E. I.du Pont de Nemours and Company.

Cover compositions may also include one or more filler(s), such as thefillers given above for rubber compositions of the present invention(e.g., titanium dioxide, barium sulfate, etc.), and/or additive(s), suchas coloring agents, fluorescent agents, whitening agents, antioxidants,dispersants, UV absorbers, light stabilizers, plasticizers, surfactants,compatibility agents, foaming agents, reinforcing agents, releaseagents, and the like.

Additional suitable cover materials are disclosed, for example, in U.S.Patent Application Publication No. 2005/0164810, U.S. Pat. No.5,919,100, and PCT Publications WO00/23519 and WO00/29129, the entiredisclosures of which are hereby incorporated herein by reference.

A moisture vapor barrier layer is optionally employed between the coreand the cover. Moisture vapor barrier layers are further disclosed, forexample, in U.S. Pat. Nos. 6,632,147, 6,932,720, 7,004,854, and7,182,702, the entire disclosures of which are hereby incorporatedherein by reference.

Compositions disclosed herein can be either foamed or filled withdensity adjusting materials to provide desirable golf ball performancecharacteristics.

The present invention is not limited by any particular process forforming the golf ball layer(s). It should be understood that thelayer(s) can be formed by any suitable technique, including injectionmolding, compression molding, casting, and reaction injection molding.

When injection molding is used, the composition is typically in apelletized or granulated form that can be easily fed into the throat ofan injection molding machine wherein it is melted and conveyed via ascrew in a heated barrel at temperatures of from 150° F. to 600° F.,preferably from 200° F. to 500° F. The molten composition is ultimatelyinjected into a closed mold cavity, which may be cooled, at ambient orat an elevated temperature, but typically the mold is cooled to atemperature of from 50° F. to 70° F. After residing in the closed moldfor a time of from 1 second to 300 seconds, preferably from 20 secondsto 120 seconds, the core and/or core plus one or more additional core orcover layers is removed from the mold and either allowed to cool atambient or reduced temperatures or is placed in a cooling fluid such aswater, ice water, dry ice in a solvent, or the like.

When compression molding is used to form a core, the composition isfirst formed into a preform or slug of material, typically in acylindrical or roughly spherical shape at a weight slightly greater thanthe desired weight of the molded core. Prior to this step, thecomposition may be first extruded or otherwise melted and forced througha die after which it is cut into a cylindrical preform. The preform isthen placed into a compression mold cavity and compressed at a moldtemperature of from 150° F. to 400° F., preferably from 250° F. to 400°F., and more preferably from 300° F. to 400° F. When compression moldinga cover layer, half-shells of the cover layer material are first formedvia injection molding. A core is then enclosed within two half-shells,which is then placed into a compression mold cavity and compressed.

Reaction injection molding processes are further disclosed, for example,in U.S. Pat. Nos. 6,083,119, 7,208,562, 7,281,997, 7,282,169, 7,338,391,and U.S. Patent Application Publication No. 2006/0247073, the entiredisclosures of which are hereby incorporated herein by reference.

COR, as used herein, is determined according to a known procedurewherein a golf ball or golf ball subassembly (e.g., a golf ball core) isfired from an air cannon at two given velocities and calculated at avelocity of 125 ft/s. Ballistic light screens are located between theair cannon and the steel plate at a fixed distance to measure ballvelocity. As the ball travels toward the steel plate, it activates eachlight screen, and the time at each light screen is measured. Thisprovides an incoming transit time period inversely proportional to theball's incoming velocity. The ball impacts the steel plate and reboundsthough the light screens, which again measure the time period requiredto transit between the light screens. This provides an outgoing transittime period inversely proportional to the ball's outgoing velocity. CORis then calculated as the ratio of the outgoing transit time period tothe incoming transit time period, COR=V_(out)/V_(in)=T_(in)/T_(out).

Golf balls of the present invention typically have an overallcompression of 30 or greater, or 40 or greater, or a compression of 30or 40 or 50 or 60 or 65 or 75 or 80 or 90 or 95 or 100, or a compressionwithin a range having a lower limit and an upper limit selected fromthese values. Dual cores of the present invention preferably have anoverall compression of 60 or 70 or 75 or 80 and an upper limit of 85 or90 or 95 or 100. Inner core layers of the present invention preferablyhave a compression of 40 or less, or from 20 to 40, or a compression ofabout 35.

Compression is an important factor in golf ball design. For example, thecompression of the core can affect the ball's spin rate off the driverand the feel. As disclosed in Jeff Dalton's Compression by Any OtherName, Science and Golf IV, Proceedings of the World Scientific Congressof Golf (Eric Thain ed., Routledge, 2002) (“J. Dalton”), severaldifferent methods can be used to measure compression, including Atticompression, Riehle compression, load/deflection measurements at avariety of fixed loads and offsets, and effective modulus. For purposesof the present invention, “compression” refers to Atti compression andis measured according to a known procedure, using an Atti compressiontest device, wherein a piston is used to compress a ball against aspring. The travel of the piston is fixed and the deflection of thespring is measured. The measurement of the deflection of the spring doesnot begin with its contact with the ball; rather, there is an offset ofapproximately the first 1.25 mm (0.05 inches) of the spring'sdeflection. Very low stiffness cores will not cause the spring todeflect by more than 1.25 mm and therefore have a zero compressionmeasurement. The Atti compression tester is designed to measure objectshaving a diameter of 42.7 mm (1.68 inches); thus, smaller objects, suchas golf ball cores, must be shimmed to a total height of 42.7 mm toobtain an accurate reading. Conversion from Atti compression to Riehle(cores), Riehle (balls), 100 kg deflection, 130-10 kg deflection oreffective modulus can be carried out according to the formulas given inJ. Dalton.

Golf balls of the present invention will typically have dimple coverageof 60% or greater, preferably 65% or greater, and more preferably 75% orgreater.

The United States Golf Association specifications limit the minimum sizeof a competition golf ball to 1.680 inches. There is no specification asto the maximum diameter, and golf balls of any size can be used forrecreational play. Golf balls of the present invention can have anoverall diameter of any size. The preferred diameter of the present golfballs is from 1.680 inches to 1.800 inches. More preferably, the presentgolf balls have an overall diameter of from 1.680 inches to 1.760inches, and even more preferably from 1.680 inches to 1.740 inches.

Golf balls of the present invention preferably have a moment of inertia(“MOI”) of 70-95 g·cm², preferably 75-93 g·cm², and more preferably76-90 g·cm². For low MOI embodiments, the golf ball preferably has anMOI of 85 g·cm² or less, or 83 g·cm² or less. For high MOI embodiment,the golf ball preferably has an MOI of 86 g·cm² or greater, or 87 g·cm²or greater. MOI is measured on a model MOI-005-104 Moment of InertiaInstrument manufactured by Inertia Dynamics of Collinsville, Conn. Theinstrument is connected to a PC for communication via a COMM port and isdriven by MOI Instrument Software version #1.2.

For purposes of the present disclosure, center hardness is obtainedaccording to the following procedure. The core is gently pressed into ahemispherical holder having an internal diameter approximately slightlysmaller than the diameter of the core, such that the core is held inplace in the hemispherical portion of the holder while concurrentlyleaving the geometric central plane of the core exposed. The core issecured in the holder by friction, such that it will not move during thecutting and grinding steps, but the friction is not so excessive thatdistortion of the natural shape of the core would result. The core issecured such that the parting line of the core is roughly parallel tothe top of the holder. The diameter of the core is measured 90 degreesto this orientation prior to securing. A measurement is also made fromthe bottom of the holder to the top of the core to provide a referencepoint for future calculations. A rough cut is made slightly above theexposed geometric center of the core using a band saw or otherappropriate cutting tool, making sure that the core does not move in theholder during this step. The remainder of the core, still in the holder,is secured to the base plate of a surface grinding machine. The exposed‘rough’ surface is ground to a smooth, flat surface, revealing thegeometric center of the core, which can be verified by measuring theheight from the bottom of the holder to the exposed surface of the core,making sure that exactly half of the original height of the core, asmeasured above, has been removed to within ±0.004 inches. Leaving thecore in the holder, the center of the core is found with a center squareand carefully marked and the hardness is measured at the center markaccording to ASTM D-2240. Additional hardness measurements at anydistance from the center of the core can then be made by drawing a lineradially outward from the center mark, and measuring the hardness at anygiven distance along the line, typically in 2 mm increments from thecenter. The hardness at a particular distance from the center should bemeasured along at least two, preferably four, radial arms located 180°apart, or 90° apart, respectively, and then averaged. All hardnessmeasurements performed on a plane passing through the geometric centerare performed while the core is still in the holder and without havingdisturbed its orientation, such that the test surface is constantlyparallel to the bottom of the holder, and thus also parallel to theproperly aligned foot of the durometer.

For purposes of the present disclosure, the outer surface hardness of agolf ball layer is measured on the actual outer surface of the layer andis obtained from the average of a number of measurements taken fromopposing hemispheres, taking care to avoid making measurements on theparting line of the core or on surface defects, such as holes orprotrusions. Hardness measurements are made pursuant to ASTM D-2240“Indentation Hardness of Rubber and Plastic by Means of a Durometer.”Because of the curved surface, care must be taken to insure that thegolf ball or golf ball subassembly is centered under the durometerindentor before a surface hardness reading is obtained. A calibrated,digital durometer, capable of reading to 0.1 hardness units is used forall hardness measurements and is set to take hardness readings at 1second after the maximum reading is obtained. The digital durometer mustbe attached to, and its foot made parallel to, the base of an automaticstand. The weight on the durometer and attack rate conform to ASTMD-2240.

It should be understood that there is a fundamental difference between“material hardness” and “hardness as measured directly on a golf ball.”For purposes of the present disclosure, material hardness is measuredaccording to ASTM D2240 and generally involves measuring the hardness ofa flat “slab” or “button” formed of the material. Hardness as measureddirectly on a golf ball (or other spherical surface) typically resultsin a different hardness value. This difference in hardness values is dueto several factors including, but not limited to, ball construction(i.e., core type, number of core and/or cover layers, etc.), ball (orsphere) diameter, and the material composition of adjacent layers. Itshould also be understood that the two measurement techniques are notlinearly related and, therefore, one hardness value cannot easily becorrelated to the other. Unless otherwise stated, the material hardnessvalues given herein for cover materials are measured according to ASTMD2240, with all values reported following 10 days of aging at 50%relative humidity and 23° C.

Thermoplastic layers of golf balls disclosed herein may be treated insuch a manner as to create a positive or negative hardness gradient, asdisclosed, for example, in U.S. patent application Ser. No. 11/939,632,filed Nov. 14, 2007; Ser. No. 11/939,634, filed Nov. 14, 2007; Ser. No.11/939,635, filed Nov. 14, 2007; and Ser. No. 11/939,637 filed Nov. 14,2007. The entire disclosure of each of these references is herebyincorporated herein by reference. In golf ball layers of the presentinvention wherein a thermosetting rubber is used, gradient-producingprocesses and/or gradient-producing rubber formulations may be employed,as disclosed, for example, in U.S. patent application Ser. No.12/048,665, filed Mar. 14, 2008; Ser. No. 11/829,461, filed Jul. 27,2007; Ser. No. 11/772,903, filed Jul. 3, 2007; Ser. No. 11/832,163,filed Aug. 1, 2007; and U.S. Pat. No. 7,410,429. The entire disclosureof each of these references is hereby incorporated herein by reference.

When numerical lower limits and numerical upper limits are set forthherein, it is contemplated that any combination of these values may beused.

All patents, publications, test procedures, and other references citedherein, including priority documents, are fully incorporated byreference to the extent such disclosure is not inconsistent with thisinvention and for all jurisdictions in which such incorporation ispermitted.

While the illustrative embodiments of the invention have been describedwith particularity, it will be understood that various othermodifications will be apparent to and can be readily made by those ofordinary skill in the art without departing from the spirit and scope ofthe invention. Accordingly, it is not intended that the scope of theclaims appended hereto be limited to the examples and descriptions setforth herein, but rather that the claims be construed as encompassingall of the features of patentable novelty which reside in the presentinvention, including all features which would be treated as equivalentsthereof by those of ordinary skill in the art to which the inventionpertains.

What is claimed is:
 1. A three-layer golf ball having a compression offrom 30 to 90 and consisting essentially of: a center having a diameterof from 1.25 inches to 1.55 inches, a center Shore C hardness(H_(center)) of from 45 to 70, an outer surface Shore C hardness(H_(core surface)) of from 80 to 95, and formed from a rubbercomposition; an intermediate layer having an outer surface Shore Chardness (H_(intermediate surface)) of from 55 to 80, a thickness offrom 0.020 inches to 0.120 inches, and formed from a highly neutralizedpolymer composition having a material hardness of from 50 Shore C to 80Shore C and comprising the reaction product of: an acid copolymer ofethylene and an α,β-unsaturated carboxylic acid, optionally including asoftening monomer selected from the group consisting of alkyl acrylatesand methacrylates; a non-acid polymer selected from the group consistingof polyolefins, polyamides, polyesters, polyethers, polyurethanes,metallocene-catalyzed polymers, single-site catalyst polymerizedpolymers, ethylene propylene rubber, ethylene propylene diene rubber,styrenic block copolymer rubbers, alkyl acrylate rubbers, andfunctionalized derivatives thereof; a cation source; and optionally, anorganic acid or salt thereof; wherein the acid copolymer is present inan amount of from 20 wt % to 90 wt % and the non-acid polymer is presentin an amount of from 10 wt % to 80 wt %, based on the combined weight ofthe acid copolymer and the non-acid polymer; and wherein greater than70% of all acid groups present in the highly neutralized polymercomposition are neutralized; and an outer cover layer having an outersurface Shore C hardness (H_(outer cover surface)) of from 82 to 99 anda thickness of from 0.020 inches to 0.080 inches; whereinH_(center)<H_(intermediate surface)<H_(core surface)<H_(outer cover surface);and wherein the difference between H_(core surface) andH_(intermediate surface) is from 5 to
 30. 2. The golf ball of claim 1,wherein the non-acid polymer of the highly neutralized polymercomposition of the intermediate layer is a maleic anhydride-modifiedpolyolefin.
 3. The golf ball of claim 1, wherein the compression of thegolf ball is from 40 to
 80. 4. The golf ball of claim 1, wherein thecompression of the golf ball is from 50 to
 75. 5. The golf ball of claim1, wherein the highly neutralized polymer composition of theintermediate layer has a solid sphere compression of from −50 to
 50. 6.The golf ball of claim 1, wherein the ratio of the overall ballcompression to the solid sphere compression of the highly neutralizedpolymer composition of the intermediate layer is <1.00.
 7. The golf ballof claim 1, wherein the outer cover layer is formed from a compositionselected from ionomers, polyurethanes, polyureas, and blends thereof. 8.The golf ball of claim 7, wherein the outer cover layer composition hasa solid sphere compression of from 80 to
 180. 9. The golf ball of claim1, wherein the intermediate layer has a thickness of from 0.030 inchesto 0.060 inches.
 10. The golf ball of claim 1, wherein the differencebetween H_(core surface) and H_(intermediate surface) is from 10 to 25.11. A four-layer golf ball having a compression of from 30 to 90 andconsisting essentially of: a dual core having an outer diameter of from1.25 inches to 1.55 inches, a center Shore C hardness (H_(center)) offrom 45 to 70, an outer surface Shore C hardness (H_(core surface)) offrom 80 to 95, and consisting of a center formed from a first rubbercomposition and an outer core layer formed from a second rubbercomposition; an intermediate layer having an outer surface Shore Chardness (H_(intermediate surface)) of from 55 to 80, a thickness offrom 0.020 inches to 0.120 inches, and formed from a highly neutralizedpolymer composition having a material hardness of from 50 Shore C to 80Shore C and comprising the reaction product of: an acid copolymer ofethylene and an α,β-unsaturated carboxylic acid, optionally including asoftening monomer selected from the group consisting of alkyl acrylatesand methacrylates; a non-acid polymer selected from the group consistingof polyolefins, polyamides, polyesters, polyethers, polyurethanes,metallocene-catalyzed polymers, single-site catalyst polymerizedpolymers, ethylene propylene rubber, ethylene propylene diene rubber,styrenic block copolymer rubbers, alkyl acrylate rubbers, andfunctionalized derivatives thereof; a cation source; and optionally, anorganic acid or salt thereof; wherein the acid copolymer is present inan amount of from 20 wt % to 90 wt % and the non-acid polymer is presentin an amount of from 10 wt % to 80 wt %, based on the combined weight ofthe acid copolymer and the non-acid polymer; and wherein greater than70% of all acid groups present in the highly neutralized polymercomposition are neutralized; and an outer cover layer having an outersurface Shore C hardness (H_(outer cover surface)) of from 82 to 99 anda thickness of from 0.020 inches to 0.080 inches; whereinH_(center)<H_(intermediate surface)<H_(core surface)<H_(outer cover surface);and wherein the difference between H_(core surface) andH_(intermediate surface) is from 5 to
 30. 12. The golf ball of claim 11,wherein the non-acid polymer of the highly neutralized polymercomposition of the intermediate layer is a maleic anhydride-modifiedpolyolefin.
 13. The golf ball of claim 11, wherein the compression ofthe golf ball is from 40 to
 80. 14. The golf ball of claim 11, whereinthe compression of the golf ball is from 50 to
 75. 15. The golf ball ofclaim 11, wherein the highly neutralized polymer composition of theintermediate layer has a solid sphere compression of from −50 to
 50. 16.The golf ball of claim 11, wherein the ratio of the overall ballcompression to the solid sphere compression of the highly neutralizedpolymer composition of the intermediate layer is <1.00.
 17. The golfball of claim 11, wherein the outer cover layer is formed from acomposition selected from ionomers, polyurethanes, polyureas, and blendsthereof.
 18. The golf ball of claim 17, wherein the outer cover layercomposition has a solid sphere compression of from 80 to
 180. 19. Thegolf ball of claim 11, wherein the intermediate layer has a thickness offrom 0.030 inches to 0.060 inches.
 20. The golf ball of claim 11,wherein the difference between H_(core surface) andH_(intermediate surface) is from 10 to 25.